Circuit breaker arrangement for preventing slow closing of breaker contacts

ABSTRACT

An electric circuit breaker having springs which discharge to close the circuit breaker contacts is provided with a motor to recharge the springs. A one-way ratchet device connected to the motor shaft prevents reverse motor rotation in the event of power loss to the motor due to spring discharge and thereby prevents the partially charged springs from discharging to cause slow closing of the contacts.

United States Patent [56] References Cited UNITED STATES PATENTS 1/1954 Favre....................'....... 11/1960 Yarrick Vitold S. Puzas Norwood; John J. Abdou, Jr., Braintree, both of,

[72] Inventors ZOO/153.16 335/76 335/76 ZOO/153.23

ZOO/153.23

ZOO/153.23

Mass. [21] Appl. No. 1,746 [22] Filed Jan. 9, 1970 [45] Patented Aug. 17, 1971 v [73] Assignee Allis-Chalmers Manufacturing Company Milwaukee, Wis;

CIRCUIT BREAKER ARRANGEMENT FOR PREVENTING SLOW CLOSING OF BREAKER CONTACTS Benson I CM". 5 Draw. Fl ABSTRACT: An electric circuit breaker having springs which g discharge to close the circuit breaker contacts is provided with I52] U.S. 200/153 a motor to recharge the springs. A one-way ratchet device 335/76 connected to the motor shaft prevents reverse motor rotation in the event of power loss to the motor due to spring discharge and thereby prevents the partia11y charged springs from discharging to cause slow closing of the contacts.

3 B2 3 b5 am 2. h

M .n F W 55 .nected-to the motorshaft.

mechanism shown in FIGSJL-andZ;

" CIRCUI'B'BREAKERARRANGEMENTEOR PREVENTING SLOW CLOSINGZ'OF BREAKER CONTACTS BACKGROUND OFLTHE INVENTION 1 1; Field of the Invention This invention"relatesgenerally to'circuit breaker operating mechanisms-.and,; particularly, to-v those -which'ernployg stored l' y' ntact, operating-.= springs :whicl care, chargeableby electric'motors.

. 2. Description.of-thePrior-Art rj Circuit i. breaker operating-:- mechanisms of the aforesaid charactenare wellknowmahd in wideusei In some; however,

accidental loss of electric-power totthe'rmotonwhile 'the'con tact; closing springsaare being charged. allows reverse motor 7 rotation and the-.springs:discharge slowlyrxthereby effecting unintentional slow closing of the circuit breaker contacts.

SUMMARY OF'THE INVENTION v,In accordance with the present invention there is-providda V circuit breaker having a support,-relatively=movable contacts =-,mounted thereon and movable: to open an'd closed; position, operating means to effect relative movement of said contacts, chargeable stored energyspringlmeans dischargeable to'effect movement of said operating means andmovement o'fisaid contactstto one of said;positions chargingmeans includingsan electric motor for charging .said stored energy spring'means, z-and .means comprising a--.oneway ratchetymechanism to prevenwslischarge of said charging means:.and:operation:xof said. contacts in the'eventthemotor is deenergize'd before said ..spring moansare fully charged.

I OBJECTS'OF IHE INVENTION t It is an object of theinvention to=-providerimproved. circuit I: breaker operatingmechanism.

, Another object is. to; provide suchoperating mechanisms which employ motor chargeablestored energy. contact operating= .springs and which. employvmeans' to preventdischarge of -'the-. springs;and.= slow closing of. the contactsin'the event. of failure of the powerlsupplyto the motor.

Another object \is to ;provide vmeans of the aforesaid cha'racterwhich comprise a ratchet me'chanismtforpreventing reverse-rotation of the, motor shaft.

"Another object is to. provide airatchedvmechanism which is mounted on the circuit breaker supportingframei-and con-- Another object is to provide means .of "the aforesaid character-.-which.arereliable in use, economical to fabricate and easyto apply.to,a widevariety. of circuitbreaker. operating mechanisms.

Other objects and advantages :of .the .invention 'will hereinafter appear.

SHRIEFJDESGRIPTION OFTHE DRAWINGS The: accompanying. drawings-.iiillustrateapoeferre'd; embodiment of'the invention; butitiswtoibewunderstoodfthati thereinbodiment illustrated :is susceptible of modifications with -respect:to.details=thereof without.departingfrom=thesscope of .theappendedclaims.

lnthedrawing: FIG.' leis aafronttendzelevational view of. aacircuit'sbreaker in .-accordancewith thetpresentinvention;

FIG .12' isasidetelevational .viewof thecircuit-breaker shown .ifiFIGL, l ewith=the .stationarycontactsshowninphantomlines;

'-FlG.-I'3.:is.:an enlarged :viewof araportion of the operating iv FIG. his .a cross-sectional view .takenxalonga'line 'IV IV :of

E'FIGEB; and i FIG. :is a perspective -'view-of auportion of'the circuit abreakershown -in F;lG.-'4 and illustrates :anotheraspect of the invention.

. 3J2 DESGR-IPTION OF THE PREFERRED EMBODIMENTS -lI-TIGS.-i1=and. 2"shown po'rtions of a circuit breaker of a low voltage type commonly used in draw out switchgear installationsf The circuit'breakercomprises a support or frame 10 on which stationary contacts 12a, 12b and 120 are understood to bernounted and which cooperate with a movable contact 14 also-mounted on frame.--l0.Mo.vable contact 14, shown in "openz'position-iinFIGiZyis movable to closed position by azdouble toggle trip-free operating mechanism, hereinafter describedywhichis mounted on frame 10 and comprises contact opening-springs16iand stored energy contact closing springs ll8. ="All referencestodirection and rotation hereinafter *ma'de are'withrespect of FIGJZ.

Closing Meehanism FIGSJ' lwarid Zshowflthe operating means or mechanism in -the'openzposition-:vvith'the *springs I8'fully charged. The

springs-"I8v can-be released either manually 'or electrically to .causei'the operating mechanism to effect closure of the relala fixedcenterr34iClockwise rotation of bellcrank 28 drives a *linkfitifto rotate a closing cam -38'which acts against a toggle roll moving a toggle linkage/42 to the right about releasable center-f44 .thus .closing breaker contact 14. When the full closed position .is'reached, the toggle linkage is propped over center.against;the= toggle 'stop'46 and is supportedthrough a 1 toggle..-latch248, a trip IatchSO/and a trip shaft 52. The closing roan-r38 will remain in the up, or closed, positionuntil the closi-ngisprings 18 are: charged. Charging of the closingsprings will rotate bellerankl28 in the counterclockwise direction thereby :drawingtheclosing cam =88 down'sintoposition for another closure.

Opening of the'rbreaker 'contacts is-accomplishedby the release ofitriplatch'50..Trip-shaft"52 is rotated counter- .elock-wise byuaction of the varioustrip devices (not shown).

'Th'isrotationof thetripshaft permits trip latch 50 to rotate counterclockwise about a fixed' center'56. Thus,2toggle latch MKis-rleasedsarid permitted to rotate: about a center 58. Rel easable center 4 4is not free to rotate with the'toggle latch 48;permitting theiforce of the stationary main contact spring aswell astheopning: springs to move cranks" 60 and 62 .clockwiseltozcollapse the togglelinkage, The rotation of cranks-=60 and 62 -andmovement of a link-64 to the left thereby opens the breaker contacts. The resetting sequence of thetiplatch;toggle latch-and toggle linkage is entirely dependention'lthe position ofitheestored energy springs 18. With the springs'charged, the. latches and'toggle -rriechanism will imniediately reset. Wi'th the springs discharged and the breaker opemtheclosingcam will hold the'toggle mechanism trip free .untilzthe. charging-sequenceis started at whichtirne the closing camfiwillbefiwithdrawn.permitting the toggles and latches to reset.

*Asto 'the' trip-free"position, when latchesSO and 48 are released,- cemen is not restrained as ina normalclosing operatiombutis released to'pivot about pin 58 as a center.

I .'Thus,:-when 'closingenergyis delivered to "the toggle linkage throughtheclosing:cam,the.toggle linkage through the closing cam,-the"toggle latch' 48 rotates'clockwise about the new center *58 ppermitting'the closing r cam to go through its vcomplete'cycle without 'moving link-64 and, therefore, the

breaker contacts Willnotclose.This-action can take place duringanyzpart of'the closingvstroke causingmovablecontact 14 to immediately returnto 'the open position even though the :storedenergyspringsare to close the mechanism.

Stored 'Energy Mechanism When the spring 18 are discharged, energization of a motor 70 by actuation of a suitable switch causes the motor shaft 72 to rotate a pinion gear 73 which drives a gear 74. Gear 74 is provided with a driving pin 76 positioned to engage with a corresponding pin 78 on an eccentric 80. The eccentric 80 is revolved clockwise about fixed center 32 driving the connecting rod 22 to the right. The motion of connecting rod 22 to the right compreses the pair of stored energy springs 18 that function as a unit through links 24 and bar 26. At the instant the springs 18 are fully charged, latch roll 82 affixed to connecting rod 22 engages prop latch thus holding the fully charged springs latched and ready to bedischarged to close the breaker either by manual release of the prop latch 20 through a mechanical closing button, or by electrical release through'the solenoid release plunger.

To guard against accidental overloading of the charging system, gear 74 that is driven by the pinion gear 73 is shaped to disengage from the pinion shaft at the full charged position ofthe stored energy springs. As FIG. 3 shows, this disengagement is accomplished by the removal of a segment of the teeth from the periphery of gear 74. Flexible teeth 84 are provided at the end of the open segment to facilitate reengagement.

Spring Charging Mechanism 1 When motor 70 is energized, it rotates pinion gear 73 in a counterclockwise direction which in turn rotates gear 74 clockwise and also rotates eccentric arm 22, so as to compress stored energy springs 18. When the cycle is complete and springs 18 are fully charged, the breaker is ready to receive a close signal. When this signal is received, the breaker contacts, through a system of linkages, will close rapidly.

Slow Close Prevention Mechanism The purpose of the present invention is to prevent the cir cuit breaker contacts 12 from slow closing, in the event that motor 70 loses its power during a spring charging cycle before springs 18 are fully charged. For example, if the power is lost to motor 70 and the stored energy springs 18 are partially charged, the springs are strong enough to rotate the motor shaft 72 in a reverse direction, which in turn would permit the circuit breaker contact to slow close.

As FIGS. 1,2, 3 and 4 show, motor 70 is mounted on frame l0 and comprises shaft 72 which extends through a plate 86 which is comprised in frame 10. As FIG. 4 shows, shaft 72 carried pinion gear 73 which is rigidly secured thereto and which cooperates with gear 74. Shaft 72 is provided with an adapter 88 which has hexagonal exterior configuration and which is secured against rotation on the shaft by apin 90. Acne-way ratchet means 92 is provided which comprises an elongated fixed member 94 and a rotatable member 96 (normally rotatable in one direction only). The fixed member 94 of ratchet means 92 is provided with a notch 98 by means of which it engages a portion of frame 10 such as the apron 99 and the rotatable member 96 of ratchet means 92 engages adapter 88 on motor shaft 72. A pin 98 and suitable washers 100 prevent lateral motion of ratchet means 92. The ratchet means 92 is thus secured in position for operation to permit rotation of motor shaft 72in one direction (counterclockwise) but not in the opposite direction (clockwise). I

If preferred, ratchet means 92 could take the form of a type of commercially available ratchet wrench of appropriatesize with the handle thereof suitably modified to adapt ,it for securement to frame 10. Thus, of motor 70 is deenergized while it is in the process of charging springs 18, the springs cannot effect reverse rotation of gear 74, gear 73 and motor shaft 72 (with subsequent slow close of the breaker contacts) because the ratchet means 92 prevents reverse rotation of the motor. Furthermore, ratchet means 92 may be provided with releasing means 102 whereby its one way operating characteristic can be selectively reversed to permit int ential slow close of the breaker contacts as during testing or for other purposes In accordance with another aspect of the invention, as shown in FIG. 5, adapter 88 on motor shaft 72 is accessible for engagement by a manually operated standard ratchet wrench 10 to permit manual movement of the circuit breaker mechanism and contacts.

The embodiments of the invention in which we claim an exclusive property or privilege are defined as follows:

1. In an electric circuit breaker,

a support,

relatively movable contacts mounted on said support and movable to open and closed positions,

contact operating means on said support to effect relative movement of said contacts,

chargeable stored energy spring means mounted on said support and dischargeable to effect movement of said contact operating means and movement of said contact to one of said positions,

charging means mounted on said support for charging said stored energy spring means,

. said charging means comprising an electric motor,

and means mounted on said support to prevent discharge of said charging means from effectingmovement of said contacts in the event said motor is deenergized before said spring means are fully charged, said means to prevent discharge of said charging means comprising one-way ratchet means which is connected to and prevents reverse rotation of the shaft of said motor,

said one-way ratchet means comprising releasing means whereby reverse rotation of said shaft of said motor can be accomplished. 

1. In an electric circuit breaker, a support, relatively movable contacts mounted on said support and movable to open and closed positions, contact operating means on said support to effect relative movement of said contacts, chargeable stored energy spring means mounted on said support and dischargeable to effect movement of said contact operating means and movement of said contact to one of said positions, charging means mounted on said support for charging said stored energy spring means, said charging means comprising an electric motor, and means mounted on said support to prevent discharge of said charging means from effecting movement of said contacts in the event said motor is deenergized before said spring means are fully charged, said means to prevent discharge of said charging means comprising one-way ratchet means which is connected to and prevents reverse rotation of the shaft of said motor, said one-way ratchet means comprising releasing means whereby reverse rotation of said shaft of said motor can be accomplished. 